PURPOSE: To enable exact formation of an elution gradient with good reproducibility by controlling a liquid feed means in such a way that the pH of a solvent mixture changes with time in the predetermined way.
CONSTITUTION: The pH of a liquid measure is measured by a measuring device 32 and a measurement signal is converted to a digital signal by an A/D converter 34. The digital signal is inputted to a processing circuit 38 for the input-output signal of a microcomputer 35. The equation of the target pH value corresponding to a desired gradient is preliminarily stored as a function of time into a storage device 37 and the signal indicating the time from a clock device 30 is substd. into the function, by which the target pH value at the present point of time is calculated. The calculated value and the signal from the device 32 are compared and the control value of the control signal to be fed to pulse motors 15, 16 is so set as to eliminate the difference therebetween. The feed rate of Varistor pumps 13 and 14 is thus controlled.
TAKEDA KENJI
NAGATA KAZUHIKO
TANAKA KOUJI
TOKUMITSU SHINICHI
TAKEDA AKIRA
KASHIMA MASARU
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